Clock monitoring is an important element of modern electronic system design. Within the functional safety market, for example, fault tolerance of a system is seen as a requirement. Fault tolerance generally refers to the ability of a system to continue operating properly, or at least in a defined and expected manner, in the event of a failure (e.g., a fault) of one or more components of the system. For a system to be considered “fault tolerant,” clock monitoring, among other elements, is often required.
In the case of security, clock monitoring is often seen as a requirement to aid systems in fending off attack. One type of attack, for example, is the inducement of a glitch in a clock signal of a system. A clock glitch may induce numerous problems such as causing a processor to skip the execution of an instruction. Skipping execution of an instruction may prevent entire portions of program code from executing. These portions of program code may provide important security features to the system such as login, encryption, decryption, and the like. If a hacker is able to cause execution of such an instruction to be skipped, the system may be vulnerable to attack.